Method and apparatus for solids processing

ABSTRACT

Apparatuses and methods for anaerobic digestion of high-solids waste are provided. The methods may include and the apparatuses may be used for moving the solid waste in a corkscrew-like fashion through a closed container. The method may further include moving the high-solids waste into contact with a heating device to facilitate the corkscrew-like movement. Other methods and apparatuses may use at least one of a partition and a conduit from which liquid or gas is discharged.

RELATED APPLICATION

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 10/217,369, filed Aug. 13, 2002, which is a divisional of U.S.patent application Ser. No. 09/534,116, filed Mar. 23, 2000 and issuedSep. 17, 2002 as U.S. Pat. No. 6,451,589, which claims priority to U.S.provisional patent application serial No. 60/161,246, filed Oct. 25,1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] The invention relates to waste-processing systems for processingmanure.

[0004] 2. Background Prior Art

[0005] Many prior art waste-processing systems are designed forlow-solids waste, such as municipal waste, that has a solids content ofapproximately one percent. High-solids wastes such as manure that have asolids content of approximately five to twelve percent either clog thesystem or are insufficiently processed. The processing of high-solidswaste has typically been performed using a plug flow process that ischaracterized by a straight-through system.

[0006] Prior art waste-processing systems for either high- or low-solidswaste use large amounts of purchased energy in the form of electricityor natural gas to generate heat and run pumps to process the wastesbecause these systems typically exhibit inefficient heating of the wasteas it is processed. In addition, prior art waste-processing systems havethe added problem of disposing of the products of their processing. Itis anticipated that stricter environmental regulations will limit theamount of waste than can be applied to fields as fertilizer because ofthe phosphates and nitrogen content of the waste. As fields reach theirlimits, other fields must be found. As the amount of unfertilized landdwindles, either other outlets for waste must be found, or a disposalmethod that meets the stricter environmental regulations must bedeveloped and used.

SUMMARY OF THE INVENTION

[0007] The apparatus and method embodying the present invention providea waste-processing system capable of processing high-solids waste. Oneaspect of the invention may provide an organic waste material processingsystem for the anaerobic digestion of high-solids waste comprising aclosed container for holding high solids waste material. The closedcontainer may include a first passage in which the waste material flowsin a first direction. The first passage may have first and second endsand the first end may include an inlet for waste material. The closedcontainer may further include a second passage in which the wastematerial flows in a second direction opposite the first direction. Thesecond passage also may have first and second ends, the second endincluding an outlet. The first passage and the second passage of theclosed container may be separated by a divider. The first passage andthe second passage may be arranged such that the second end of the firstpassage is adjacent the first end of the second passage, and the firstend of the first passage is adjacent the second end of the secondpassage. In one embodiment, the container may be used for movinghigh-solids waste in a corkscrew-like fashion through at least one ofthe first passage and the second passage.

[0008] In another aspect, the invention may or may not provide awaste-processing system utilizing a heating device containing heatingmedium and a partition. A conduit having nozzles may or may not beutilized. A liquid or gas may be discharged therefrom to further agitatethe waste material.

[0009] In another aspect, the invention may provide a method for theanaerobic digestion of high-solids waste. The method comprises movingthe solid waste in a corkscrew-like fashion through the container. Themethod may or may not further comprise moving the high-solids waste intocontact with a heating device in the closed container, and/or using aconduit from which liquid or gas is discharged, to facilitate themovement of the solid waste in a corkscrew-like fashion.

[0010] Other features and aspects of the invention are set forth in thefollowing drawings, detailed description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a schematic view of a waste processing system embodyingthe invention.

[0012]FIG. 2 is a partial cross-section elevational view of the digesterof the waste processing system shown in FIG. 1.

[0013]FIG. 3 is a cross-section elevational view of a wall between amixing chamber and the digester and taken along the 3-3 line of FIG. 1.

[0014]FIG. 4 is a partial cross-section elevational view of a clarifier,taken along the 4-4 line of FIG. 1.

[0015]FIG. 5 is a perspective view of a composter of the wasteprocessing system shown in FIG. 1.

[0016]FIG. 6 is a cross-sectional view of the composter taken along the6-6 line in FIG. 5.

[0017]FIG. 7 is a flowchart of the process employed in the wasteprocessing system shown in FIG. 1.

[0018]FIG. 8 is a view similar to FIG. 7 and shows an alternativeprocess of the invention.

[0019]FIG. 9 is a view similar to FIGS. 7 and 8 and shows anotheralternative process of the invention.

[0020]FIG. 10 is a view similar to FIGS. 7-9 and shows anotheralternative process of the invention.

[0021]FIG. 11 is an enlarged view of a portion of the waste processingsystem shown in FIG. 1.

[0022]FIG. 12 is a schematic view of an alternative waste processingsystem embodying the invention.

[0023]FIG. 13 is a partial cross-sectional view of a digester takenalong the 13-13 line in FIG. 12.

[0024]FIG. 14 is a partial cross-section elevational view of thedigester taken along the 14-14 line in FIG. 12.

[0025] Before one embodiment of the invention is explained in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangements of the componentsset forth in the following description or illustrated in the drawings.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways. Also, it is understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof herein is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items.

DETAILED DESCRIPTION OF INVENTION

[0026] A waste-processing system 10 embodying the invention isillustrated in FIGS. 1-10. FIGS. 1-6 show the apparatus in which theprocess is conducted. The system 10 is described in terms of processingmanure, but may also be used to process wood pulp, municipal wastes, ororganic waste products in general.

[0027]FIG. 1 shows schematically the apparatus used to processhigh-solids farm waste. A digester enclosure 20 includes three majorsections: a mixing chamber 30, a digester 40, and a clarifier 50. Thedigester enclosure 20 is arranged such that a relatively large digester40 may be built in relatively small space.

[0028]FIG. 2 illustrates the construction of an outside wall 54 of thedigester enclosure 20. The height of the outer wall 54 of the digesterenclosure 20 is approximately 17 feet, with a liquid depth 58 in thedigester enclosure 20 of approximately 14 feet and a biogas storage area59 of about 18 inches above the liquid 58. A footing 62 provides aninterface between the wall 54 and the ground 66, and supports the wall54 and the edge 70 of the floor 74. Both the footing 62 and the wall 54are constructed of poured concrete. The wall 54 is approximately twelveinches thick at the lower end 78 of the wall 54, and approximately eightinches thick at the upper end 82 of the wall. The floor 74 of thedigester enclosure 20 is approximately four inches of concrete.Insulation 86 with a thickness of approximately four inches may bearranged below the floor 74 and provides an interface between the floor74 and the ground 66.

[0029] The roof 90 of the digester enclosure 20 is located approximately15 feet, 8 inches above the floor 74 of the digester enclosure 20. Theroof 90 is constructed of an approximately ten-inch thickness 98 ofSPANCRETE concrete topped by a layer of insulation 94 with a thicknessbetween four and eight inches, and more particularly, between three andfour inches.

[0030] A bio gas storage chamber 102 may be located above the roof 90.The primary component of the chamber 102 is a liner 106 including anupper liner section 110 and a lower liner section 114. The liner 106 ispreferably constructed from high-density polyethylene (HDPE), but may beany other suitable material. The liner 106 is sealed around the edges118 of the liner 106 by capturing the edges 118 beneath six-inch channeliron 122, which is removably attached to the digester enclosure walls 54using nuts 126 on a plurality of anchor bolts 130 embedded in thedigester enclosure wall 54. A ten-inch PVC pipe 134 is inserted aroundthe periphery of the chamber 102 within the liner 106 to assist inmaintaining the seal around the periphery of the liner 106. The liner106 is constructed such that it can flexibly fill with bio gas as thebio gas is produced in the digester 40, and can be emptied of bio gas asis needed. The bio gas storage chamber 102, as an addition to biogasstorage 59 within the digester enclosure 20, may be replaced by anyother suitable gas storage system including a roofed storage system.

[0031] Returning to FIG. 1, the mixing chamber 30 has horizontaldimensions of approximately 36 feet by 15 feet. Arranged within themixing chamber 30 is approximately 2000 feet of three or four-inch blackheating pipe 142, which is designed to carry hot water to heat sludge144 within the mixing chamber 30. An influent pipe 148 carries manure336 into the mixing chamber 30. The closed container may further includea heating device and may or may not include a partition. The heatingdevice may comprise a conduit containing a liquid or gas with dischargenozzles to further agitate the waste material, positioned to heat wastematerial to form heated waste material. Mixing within the mixing chamber30 is provided by at least one of a system of mixing nozzles utilizingrecirculated biogas (the nozzles being on the end of an activated sludgerecirculation pipe 147) and convective flow resulting from the heatingof the manure 336 by the heating pipe 142. In one embodiment, therecirculation pipe may deliver effluent to the digester 166, in anotherembodiment to the mixing chamber 30. If required, a standard auger 146used for removing solids from the mixing chamber 30 is arranged near thefloor 150 of the mixing chamber 30 such that it can transport solidsfrom the floor 150 of the mixing chamber 30 through the wall 154 of themixing chamber 30 and to a collection device 158. The collection device158 is optional. In another embodiment (not shown), solids may beremoved from the mixing chamber 30 by any other suitable system, such asa sump pump.

[0032] As illustrated in FIG. 3, a cutout 160 formed in the wall 162between the mixing chamber 30 and the digester 40 allows sludge to flowfrom the mixing chamber 30 into the digester 40. In addition, removablepanels 161 may be positioned to block opening 163 in the wall 162. Theremovable panels shown in FIG. 3 are optional. Removable panels 161 maybe removed as needed to allow greater flow from mixing chamber 30 todigester 40, if desired.

[0033] Returning to FIG. 1, the digester 40 is a generally U-shaped tankwith overall horizontal dimensions of approximately 100 feet long and 72feet wide. A center wall 165 approximately 90 feet in length divides thedigester 40 into the two legs 166, 170 of the U-shape. Thus each leg166, 170 of the digester 40 is approximately 100 feet long and 36 feetwide.

[0034] The first leg 166 of the digester 40 includes approximately 800feet of three or four-inch black heating pipe 174 through which heatedwater or gas can flow. The heating pipe 174 is or separate gas pipes arearranged along the center wall 165. The second leg 170 of the digester40 includes approximately 200 feet of four-inch black heating pipe 178,which is also arranged along the center wall 165. In another embodimentillustrated in FIG. 11, the heating pipes 174, 178 or separate gas pipes178 may include jet nozzles 180 to dispense heated gas or recycledbiogas into the sludge 144.

[0035] In addition to producing activated sludge 184, the anaerobicdigestion of the digester 40 also produces bio gas in the form ofmethane gas, which is collected in the space above the liquid indigester 40 and below the roof 98 and can also be stored in the gasstorage chamber 102. Any liquid that condenses within the chamber 102 isdirected through the effluent pipe 196 (see FIGS. 7-9) to the liquidstorage lagoon 198 (see FIGS. 7-9). The collected bio gas is used tofuel an internal combustion engine 138 (see FIG. 7) that, in combinationwith an electric generator, is used to produce electricity that is soldto a power utility 332 (see FIG. 7). The cooling system of the internalcombustion engine 138 also produces hot coolant that is used for heatingand agitation in the mixing chamber 30 and, alternatively, for heatingand agitation in the mixing chamber 30 and digester 40. Hot water fromthe engine 138 passes through an air/water cooler 334 (see FIG. 7) toreduce the temperature of the water from the approximately 180° F.temperature at the exit of the engine 138 to approximately 160° F. foruse in the mixing chamber 30 and the digester 40.

[0036] As shown in FIG. 1, the optional clarifier 50 is located adjacentthe digester 40 beyond clarifier panels 182 and adjacent the mixingchamber 30. The clarifier 50 has horizontal dimensions of approximately36 feet by 21 feet, and is largely empty of any equipment or hardware,with the exception of an equipment room 183. Turning to FIG. 4, theclarifier panels 182 are constructed from HDPE and form a partialbarrier between the digester 40 and the clarifier 50. The clarifierpanels 182 cover the entire horizontal dimension across the clarifier 50from center wall 165 to outer wall 54. Separation panels 186 within theclarifier 50 serve to direct solids in a downward direction to thebottom 190 of the clarifier 50, where the solids collect in a sump 194.Sump pipe 198 leads to a standard solids press 214 (see FIGS. 7-9), andto the activated sludge recirculation pipe 147 carrying activated sludge184 to the mixing chamber 30, or, alternatively, the digester 40 (seeFIG. 1).

[0037] As illustrated in FIGS. 7-9, a portion of the liquid produced asa result of the operation of the solids press 214 may be recycled to themixing chamber 30 or the digester 40 for further processing.

[0038] Returning to FIG. 4, liquids in the clarifier 50 decant throughgap 202 and collect in a liquid sump 206. A liquid effluent pipe 210within the liquid sump 206 leads through a heat exchanger 340 (see FIG.7) and to a liquid storage lagoon 198 (see FIG. 7).

[0039] A composter 220 as illustrated in more detail in FIGS. 5 and 6 islocated downstream of the solids press 214. The composter is optional.The primary components of the composter 220 include a water tank 224 anda composting barrel 228. The water tank 224 is generally a rectangularparallelepiped with six-inch-thick walls 230 constructed from concrete.A four-inch layer of insulation 232 (not shown in FIG. 6) covers theperiphery of the walls 230. A sump 236 is located in the floor 240 ofthe water tank 224. Extending through the floor 240 of the water tank224 is an air supply pipe 244. A port 248 in the first wall 252 of thewater tank 224 accommodates a sludge supply pipe 256 that connects thesolids press 214 with the composter barrel 228. A port 260 in the secondwall 264 of the water tank 224 accommodates a composter solids exit pipe268.

[0040] The water level 272 of the water tank 224 may be varied toprovide buoyant support to the composter barrel 228; the water level 272as illustrated in FIGS. 5 and 6 is representative of a typical level.The water 276 is typically at 140-160° F. A water inlet pipe 280provides a flow of water 276 to the composter barrel 228 and the watertank 224. The water 276 is supplied from the cooler 334 of engine 138.

[0041] The composter barrel 228 defines an interior chamber 232. Asludge supply auger 284 is located within the sludge supply pipe 256 andextends from within the sludge supply pipe 256 into chamber 232 of thebarrel 228. A composted solids exit auger 288 extends from withinchamber 232 of barrel 228 into the composter solids exit pipe 268. Eachpipe 256, 268 is connected to the ends 292, 294 of the composter barrel228 using a double rotating union seal with an internal airpressure/water drain (not shown). The pipes 256, 268 and augers 284, 288are designed such that air that is necessary for drying the sludge andfor aerobic digestion may pass through the composter barrel 228. Airpasses through solids exit pipe 268 and air inlet pipe 266, into thecomposter barrel 228, and out through air outlet pipe 258 and sludgesupply pipe 256. The air pipes 258, 266 extend vertically to keep theirends 270 above the activated sludge 184 in the composter barrel 228.

[0042] The composter barrel 228 is generally cylindrical andapproximately 100 feet long and 10 feet in diameter. A plurality of wearbars 296 is attached to the exterior circumference of the barrel 228.Rubber tires 300 acting on the wear bars 296 serve to hold the composterbarrel 228 in position.

[0043] As illustrated in FIGS. 5 and 6, a plurality of vanes 304 isattached to the barrel 228. These vanes 304 extend between the third andfourth wear bars 308, 312. The vanes 304 are generally parallel to thelongitudinal axis of the composter barrel 228. As shown in FIG. 6, toeffect cooperation with the vanes 304, the water inlet pipe 280 and theair inlet pipe 244 are laterally offset in opposite directions from thevertical centerline of the composter barrel 228. As a result, when water276 flows from the water inlet pipe 280, the water 276 collects on thevanes 304 on a first side 316 of the composter barrel 228, and when air320 flows from the air inlet pipe 244, air 320 collects under the vanes304 on a second side 318 opposite the first side 316 of the composterbarrel 228. The lateral imbalance resulting from weight of water 276 onthe first side 316 of the barrel 228 and the buoyancy of the air 320 onthe second side of the barrel 228 causes the barrel 228 to rotate in aclockwise direction as viewed in FIG. 6.

[0044] The composter barrel 228 is slightly declined toward the exit end294 of the composter barrel 228 to encourage the activated sludge 184within the composter barrel 228 to move along the longitudinal axis ofthe composter barrel 228 toward the exit end 294. As shown in FIG. 6,the composter barrel 228 also includes internal baffles 296 that serveto catch and turn the activated sludge 184 as the composter barrel 228rotates.

[0045] As illustrated in FIG. 1, the composter solids exit pipe 268connects to a standard bagging device 324 that places the compostedsolids into bags 328 for sale.

[0046] In operation of the waste-processing system 10, as illustrated inFIGS. 1 and 7, unprocessed cow manure 336 from area farms and othersources is transported to the waste processing site and transferred to aheat exchanger 340 where, if necessary, the manure 336 is thawed usingwarm water from the clarifier 50 by way of liquid effluent pipe 210.

[0047] Manure 336 is then transferred from the heat exchanger 340 to themixing chamber 30 through influent pipe 148, where the manure 336 may,alternatively, be mixed with activated sludge 184 recycled from theclarifier 50 by way of activated sludge recirculation pipe 147 to becomesludge 144. The sludge 144 is heated to approximately 95-130° Fahrenheitby directing coolant at approximately 160° F. from the engine cooler 334through the mixing chamber heating pipes 142. In addition, if required,solids such as grit fall to the bottom of the mixing chamber 30 underthe influence of gravity and are removed using the mixing chamber auger146. The solids are then transferred to a disposal site.

[0048] After a stay of approximately one day in the mixing chamber 30,the sludge 144 flows through cutout 160 or opening 163 in the wall 162and into the digester 40, where anaerobic digestion takes place. Theactivated sludge 184 added to the manure 336 in the mixing chamber 30 ordigester 40 serves to start the anaerobic digestion process.

[0049] The apparatus and method described herein employ modified plugflow or slurry flow to move the sludge, unlike the plug flow in priorart systems. The digester heating pipes 174, 178 locally heat the sludge144 using hot water at approximately 160° F. from the cooler 334 of theengine 138, causing the heated mixed sludge to rise under convectiveforces. The convection develops a current in the digester 40 that isuncharacteristic of prior art high-solids digesters. Sludge 144 isheated by the digester heating pipes 174, 178 near the digester centerwall 165, such that convective forces cause the heated sludge 144 torise near the center wall 165. At the same time, sludge 144 near therelatively cooler outer wall 54 falls under convective forces. As aresult, the convective forces cause the sludge 144 to follow a circularflow path upward along the center wall 165 and downward along the outerwall 54. At the same time, the sludge 144 flows along the first andsecond legs 166, 170 of the digester 50, resulting in a combinedcorkscrew-like flow path for the sludge 144.

[0050] In another embodiment (not shown), hot gas injection jets usingheated gases from the output of the engine 138 replace the hot waterdigester heating pipes 174, 178 as a heating and current-generatingsource. The injection of hot gases circulates the sludge 144 throughboth natural and forced convection. A similar corkscrew-like flow pathis developed in the digester 40.

[0051] As shown in FIG. 11, to further increase upward flow of theheated sludge 14 near the center wall 165, biogas may be removed fromthe biogas storage area 59 in the digester 40, pressurized with a gascentrifugal or rotary-lobe blower, and injected into the heated sludge144 through nozzles 376 positioned onto conduit 378. This recycledbiogas injection near the floor 74 of the digester 40 serves to increasethe rapidity of the cork-screw-like flow path for the heated sludge 144.

[0052] In the arrangement shown in FIG. 1, the U-shape of the digester40 results in a long sludge flow path and thus a long residence time ofapproximately twenty days. As the sludge 144 flows through the digester40, anaerobic digestion processes the sludge 144 into activated sludge184. The anaerobic digestion process also reduces the phosphate contentof the liquid effluent after solids removal, by approximately fiftypercent, which is a key factor in meeting future environmentalregulations.

[0053] From the digester 40 the activated sludge 184 flows into theoptional clarifier 50. The clarifier 50 uses gravity to separate theactivated sludge 184 into liquid and solid portions. Under the influenceof gravity and separation panels 186, the liquid portion rises to thetop of the mixture and is decanted through a gap 202 into a liquid sump206. It is later transferred to lagoon storage 198 through effluent pipe210. The liquid is then taken from the lagoon 198 for either treatmentor use as fertilizer.

[0054] The solid portion of the activated sludge 184 settles to thebottom 190 of the clarifier 50 in sump 194. From there, approximatelyten to twenty-five percent of the activated sludge 184 is recycled tothe digester 40 or mixing chamber 30 through activated sludgerecirculation pipe 147 to mix with the incoming manure 336, as describedabove. The remaining approximately seventy-five to ninety percent of theactivated sludge 184 is removed from the clarifier 50 through sump pipe198 and is transferred to the solids press 214 in which the moisturecontent of the activated sludge 184 is reduced to approximatelysixty-five percent.

[0055] From the solids press 214, the activated sludge 184 istransferred through sludge supply pipe 256 using sludge supply auger 284to the interior chamber 232 of the composter barrel 228 where theactivated sludge 184 is heated and agitated such that aerobic digestiontransforms the activated sludge 184 into usable fertilizer. Outsidebulking compost material can be added to the chamber 232 to make thefertilizer more suitable for later retail sale. As the composter barrel228 turns, baffles 296 within the chamber 232 agitate and turn thesludge. This agitation also serves to aerate the sludge to enhanceaerobic digestion. At the same time, the tank of water 224 in which thebarrel 228 sits heats the barrel 228. This heating also promotes aerobicdigestion.

[0056] In the preferred embodiment, water 276 falling from the waterinlet pipe 280 and air 320 rising from the air inlet pipe 244 collectson the vanes 304 and causes the composter barrel 228 to turn around itslongitudinal axis. In other embodiments, direct motor or belt drives, orany other suitable drive mechanism may turn the composter barrel 228.

[0057] As the activated sludge 184 turns over and undergoes aerobicdigestion in the chamber 232, it also travels longitudinally andeventually exits the composter barrel 228 through the composter solidsexit pipe 268, driven by the composter solids exit auger 288. Theprocessed sludge, which has become usable fertilizer at approximatelyforty-percent moisture, is transferred to a bagging device 324. In thebagging device 324, the processed sludge is bagged for sale asfertilizer.

[0058] In an alternative embodiment illustrated in FIG. 8, a turbine 139replaces the internal combustion engine as described above. The turbine139 is preferably an AlliedSystems TURBOGENERATOR turbine power systemas distributed by Unicom Distributed Energy, but may be any othersuitable turbine. The turbine 139 is fueled by the methane collected inthe bio gas storage chamber 59 or 102. The differences with the use of aturbine 139 from the previously-discussed process are outlined asfollows. Instead of an engine cooler 334 producing heated coolant, theturbine 139 produces exhaust gases at approximately 455° F. The hotexhaust gases are used to heat water in a closed loop 335 through anair/water heat exchanger 337. The heated water is then used for heatingin the mixing chamber 30 and for heating and agitation in the digester40. This embodiment is used in conjunction with a composter (not shown)as described above.

[0059] As shown in FIG. 8, the composter is replaced with a solids dryer218 in which hot exhaust from the turbine 139 or reciprocating engine138 is used to dry the sludge taken from the solids press 214. From thesolids dryer 218, the activated sludge 184 is transferred to a baggingdevice 324. In the bagging device 324, the processed sludge is baggedfor sale as fertilizer.

[0060] In another embodiment illustrated in FIG. 9, hot exhaust gasesfrom the turbine 139 are used to heat methane from the bio gas storagechamber 102 to approximately 160° F. in an air/air heat exchanger 220.The heated methane is then injected into the mixing chamber 30 and thedigester 40 for heating and agitation. In this embodiment, it ispossible to seal off the digester 40 from any air contamination becauseonly methane is used for heating and agitation. The methane is thenrecaptured in the bio gas storage chamber for reuse. This embodiment isused in conjunction with a composter (not shown) as described above.

[0061] In the embodiment illustrated in FIG. 9, the composter isreplaced with a solids dryer 218 in which hot exhaust from the turbine139 is used to dry the sludge taken from the solids press 214. Again,from the solids dryer 218, the activated sludge 184 is transferred to abagging device 324. In the bagging device 324, the processed sludge isbagged for sale as fertilizer.

[0062] In still another embodiment illustrated in FIG. 10, a fluidizingbed dryer 350 takes the place of the composter or solids dryer describedin previous embodiments. Pressed bio solids at approximately 35 percentsolids from the solids press 214 enter the fluidizing bed dryer 350where the solids are fluidized using heated air in a closed-loop airsystem 354. This fluidizing results in moisture from the bio solidsbeing entrained in the heated air. The moisture-laden heated air passesthrough a water condenser 358 where water is removed from the heated airand circulated back to the heating pipe 142 in the mixing chamber 30 andto the heating pipe 174 in the digester 40. Heat is provided to theclosed-loop air system 354 through an air/air heat exchanger 362. Hotexhaust gases from a series of turbines 139 provide heat to the air/airheat exchanger 362. The exhaust gases then enter the water condenser 358to remove combustion moisture from the turbine exhaust before theremaining gases are vented to the atmosphere. The water condenser 358,in addition to recapturing water, also recaptures heat carried by theturbine exhaust and by the heated air in the closed-loop air system 354.This recaptured heat is used to heat the water circulating in theclosed-loop water heating system.

[0063] The combination of a fluidizing bed dryer 350 and an air/air heatexchanger 362 recaptures heat produced by the turbines 139 that wouldotherwise be lost in the turbine exhaust. The heated air in thefluidizing bed dryer 350 evaporates water carried in the effluent fromthe solids press. The latent heat of vaporization carried by themoisture in the air leaving the fluidizing bed dryer 350 issubstantially recaptured in the water condenser 358. The closed-loop airsystem 354 allows for air with reduced oxygen content to be used in thefluidizing bed dryer 350 to reduce the risk of fire associated withdrying organic material. In addition, the closed-loop air system 354allows for the addition of an auxiliary burner (not shown) if needed toprocess wetter material in the fluidizing bed dryer 350. A variablespeed fan (not shown) can be added to the closed-loop air system 354after the water condenser 358 to pressurize the air for the fluidizingbed dryer 350.

[0064] In the embodiment illustrated in FIG. 10, from the solids dryer218, the activated sludge 184 is transferred to the bagging device 324.In the bagging device 324, the processed sludge is bagged for sale asfertilizer.

[0065] In another embodiment (not shown), the composter is replaced witha solids dryer 218 in which hot exhaust from the internal combustionengine 138 is used to dry the sludge taken from the solids press 214.Again, from the solids dryer 218, the activated sludge 184 istransferred to a bagging device 324. In the bagging device 324, theprocessed sludge is bagged for sale as fertilizer.

[0066]FIG. 12 illustrates another embodiment of the waste processingsystem of the present invention, wherein like elements have likenumerals. Specifically, FIG. 12 illustrates a waste processing system10′, which includes a digester enclosure 20′, a mixing chamber 30′, adigester 40′ and a clarifier 50′. A center wall 65′ divides the digester40′ into a first leg 166′ and a second leg 170′. The sludge 144 cantherefore move from the mixing chamber 30′ into the digester 40′ alongthe first leg 166′ in a first direction, and toward the clarifier 50′along the second leg 170′ of the digester 40′ in a second directionopposite the first direction.

[0067] The first leg 166′ and the second leg 170′, as illustrated inFIG. 12, each include a partition 370 positioned relative to the centerwall 65′ such that a space 380 is created between the partition 370 andthe center wall 65′. The partition may comprise at least one of a rigidboard or plank, curtain or drape, tarp, film, and a combination thereof.In addition, the partition may be constructed of a variety of materials,including without limitation, at least one of a metal, wood, polymer,ceramic, composite, and a combination thereof. The first leg 166′ andthe second leg 170′ each further include a heating device 372 positionedwithin the space 380 between the partition 370 and the center wall 65′such that sludge 144 or activated sludge 184 (referred to from thispoint forward as sludge 144 for simplicity) is heated as it contacts theheating device 372. Heated sludge 144 rises relative to cooler sludge144 by free convection and is allowed to rise upwardly within the space380.

[0068] The heating device(s) 372 and the partition(s) 370 are shown ingreater detail in FIGS. 13 and 14. For simplicity, one of the heatingdevices 372 and the partitions 370 will be described in greater detail,but it should be noted that the description may equally apply to theother heating device 372 and partition 370. As shown in FIGS. 13 and 14,the heating device 372 includes a series of conduits 374, eachcontaining a heating medium. A variety of heating media may be used withthe present invention, including at least one of water and a gas. Theconduits 374 do not all need to contain the same heating medium. Thatis, some of the conduits 374 may contain a gas, while others contain aliquid, such as water.

[0069] As illustrated in FIGS. 13 and 14, the waste processing system10′ may further include at least one conduit 378, which contains acompressed, recycled biogas from the biogas storage area 59 and hasnozzles 376. The nozzles 376 are gas outlets. The compressed biogascontained in the conduit 378 flows through the conduit 378 and out thenozzles 376, such that as the gas escapes the conduit 378 via thenozzles 376, the gas is propelled upwardly in the space 380 to promotethe sludge 144 to move upwardly through the principle of air/waterlifting. FIGS. 13 and 14 illustrate two conduits 378 having nozzles 376.Any number of conduits 378 having nozzles 376 can be used withoutdeparting from the spirit and scope of the present invention. Thenozzles 376 may be simple holes drilled into conduit 378 or may bespecialized nozzles 376 attached to conduit 378 via welding or tapping.

[0070] Referring to FIGS. 13 and 14, a frame 364 is positioned withinthe space 380 to support the heating device 372 and the conduits 378.The frame 364 is illustrated as comprising a plurality of ladder-likeunits 365 and a connecting bar 369 running generally parallel to thecenter wall 65′ to connect the units 365. Each unit 365, as illustratedin FIGS. 13 and 14, is formed of two vertical columns 366 positioned onopposite sides of the space 380 and a plurality of crossbeams 368connecting the two vertical columns 366 across the space 380. The frame364 is illustrated by way of example only, and the present invention isin no way limited to the illustrated support structure. A variety offrame elements can be used to support the heating device 372, conduits378, and/or other components of the waste processing system 10′ withinthe space 380 without departing from the spirit and scope of the presentinvention.

[0071] As illustrated in FIGS. 13 and 14, the partition 370 has a topedge 371 and a bottom edge 373. In addition, the illustrated partition370 is substantially vertical and shorter in height than the digester40′, such that heated sludge 144 can move over the top edge 371 of thepartition 370 and out of the space 380 between the partition 370 and thecenter wall 65′, and cooled sludge 144 can move under the bottom edge373 of the partition 370 and into the space 380. Therefore, asillustrated by the arrows in FIGS. 13 and 14, the partition 370, inconjunction with the heating device 372, promotes upward and downwardmovement of the sludge 144. This upward and downward movement of thesludge 144 results in an overall spiral movement of the sludge 144 asthe sludge 144 is moved along the first and second legs 166′, 170′ ofthe digester 40′. Further promoting this spiral motion are the twoconduits 378 with nozzles 376, which are located beneath the series ofconduits 374 of the heating device 372 in FIGS. 13 and 14. The spiralmotion of the sludge 144 throughout the digester 40′ promotes thermalmixing of the sludge 144 to produce activated sludge 184.

[0072] The series of conduits 374 illustrated in FIGS. 12-14 is formedby having a two-by-five configuration within the space 380 (i.e. twoconduits 374 across and five conduits 374 up and down), with theconduits 374 running generally parallel to the center wall 65′. Anotherexample is a two-by-six configuration, as shown in FIG. 13. In addition,two conduits 378 having nozzles 376 also run generally parallel to thecenter wall 65′ and are positioned beneath the series of conduits 374just described. It should be noted, however, that any number of conduits374 containing heating medium, and any number of conduits 378 havingnozzles 376 arranged in a variety of configurations can be used withoutdeparting from the spirit and scope of the present invention. The seriesof conduits 374 and the conduits 378 having nozzles 376 depicted inFIGS. 12-14 are shown by way of example only.

[0073] Various features of the invention are set forth in the followingclaims.

What is claimed is:
 1. An organic waste material processing system forthe anaerobic digestion of high-solids waste, the waste materialprocessing system comprising: a closed container for holding high solidswaste material, the closed container including a first passage in whichthe waste material flows in a first direction, the first passage havingfirst and second ends, the first end including an inlet for wastematerial, a second passage in which the waste material flows in a seconddirection opposite the first direction, the second passage having firstand second ends, the second end including an outlet, the first passagebeing separated from the second passage by a divider, the second end ofthe first passage being adjacent the first end of the second passage,and the first end of the first passage being adjacent the second end ofthe second passage; a heating device containing heating medium andpositioned to heat the waste material to form heated waste material; anda partition.
 2. The organic waste material processing system of claim 1,wherein the heating device is positioned adjacent a wall of the closedcontainer in at least a portion of at least one of the first passage andthe second passage to cause thermal mixing of the waste material.
 3. Theorganic waste material processing system of claim 1, wherein the closedcontainer further includes a conduit having at least one gas outletpositioned to promote upward movement of the heated waste materialutilizing recycled biogas.
 4. The organic waste material processingsystem of claim 1, wherein the partition is positioned relative to thedivider such that a space is created between the partition and thedivider, and wherein the heating device is positioned within the spacefor heating the waste material and enabling heated waste material toflow upwardly within the space.
 5. The organic waste material processingsystem of claim 1, wherein the partition is positioned relative to awall of the closed container such that a space is created between thepartition and the wall, and wherein the heating device is positionedwithin the space for heating the waste material and enabling heatedwaste material to flow upwardly within the space.
 6. The organic wastematerial processing system of claim 1, wherein the partition has a topedge and a bottom edge, the top edge being spaced a distance from a topof the closed container, and the bottom edge being spaced a distancefrom a bottom of the closed container.
 7. The organic waste materialprocessing system of claim 1, wherein the partition is positioned suchthat a space is created between the partition and a wall of the closedcontainer through which heated waste material moves in an upwardlydirection.
 8. The organic waste material processing system of claim 7,wherein the heating device is positioned within the space.
 9. Theorganic waste material processing system of claim 7, wherein thepartition has a top edge over which heated waste material moves out ofthe space.
 10. The organic waste material processing system of claim 7,wherein the partition has a bottom edge under which waste material movesinto the space.
 11. The organic waste material processing system ofclaim 1, wherein the heating device comprises a conduit.
 12. The organicwaste material processing system of claim 1, wherein the heating mediumcomprises water.
 13. The organic waste material processing system ofclaim 1, wherein the heating medium comprises a gas.
 14. The organicwaste material processing system of claim 1, wherein the heating deviceand the partition are positioned to promote a corkscrew-like movement ofthe waste material such that heated waste material moves generallyupward and cooled waste material moves generally downward as the wastematerial flows in at least one of the first direction and the seconddirection.
 15. A method for the anaerobic digestion of high-solidswaste, the method comprising: providing a closed container including afirst passage in which the waste material flows in a first direction,the first passage having first and second ends, the first end includingan inlet for waste material, and a second passage in which the wastematerial flows in a second direction opposite the first direction, thesecond passage having first and second ends, the second end including anoutlet, the first passage being separated from the second passage by adivider, the second end of the first passage being adjacent the firstend of the second passage, and the first end of the first passage beingadjacent the second end of the second passage; and moving thehigh-solids waste in a corkscrew-like fashion through at least one ofthe first passage and the second passage.
 16. The method of claim 15,further comprising contacting the high-solids waste with a heatingdevice to facilitate the corkscrew-like movement.
 17. The method ofclaim 16, further comprising using a conduit from which liquid or gas isdischarged to facilitate the corkscrew-like movement.
 18. The method ofclaim 15, further comprising using a conduit from which liquid or gas isdischarged to facilitate the corkscrew-like movement.
 19. A method forthe anaerobic disgestion of high-solids waste, the method comprising:moving the high-solids waste into contact with a heating device in aclosed container; and moving the solid waste in a corkscrew-like fashionthrough the container.
 20. The method of claim 19, further comprisingusing a conduit from which liquid or gas is discharged to facilitate themovement of the solid waste in a corkscrew-like fashion.
 21. The methodof claim 20, wherein the conduit discharges gas, and the gas is recycledbiogas.